单数句变复数句是七年级英语试题中的一个题型. 记住以下几要素即可迎刃而解：
1、人称代词主格单数变成相应的人称代词主格复数，即I-we; you-you; she/he/it-they
She is a girl. -They are girls.
2、 am, is变为are.
I am a student. We are students.
3、 不定冠词a/an要去掉或者变为some, any(肯定句及希望得到对方肯定回答的疑问句用some, 否定和疑问句用any)如：
He is a boy. They are (some) boys.
4、普通单数名词要变为复数形式。
It is a cat. They are cats.
5、指示代词this, that变为these, those.如：
This is a book. These are books.
6、Man, woman做定语修饰可数名词时，要在“数”上与被修饰名词保持一致，但其他名词修饰名词表示“性质”时，不作变化。如：
This is a woman doctor.
They are women doctors.
This is an ornage tree.
They are ornage trees.
7、反身单词也要变相应的复数形式。
myself-ourselves yourself-yourselves himself/herself/itself-themselves
I am teaching myself computer.
We are teaching ourselves computer.
8、物主代词由单数变复数：
名词性物主代词：mine-ours yours-yours his/hers/its-theirs
形容词性主代词：my-our your-you his/her/its-their
This book is mine.—The books are ours.
This is her pen. – These are their pens.
一般情况下，形容词性物主代词在单数句变复数句时不变。当句中形容词性物主代词与句中的主语一致时，形容词性物主代词应随主语人称的变化而变化，仍要保持一致。
This is my pen. These are my pens.
He likes his bike. They like their bikes.
注意：单数句变为复数句时，句中的形容词、定冠词、副词、疑问词、介词短语和感叹词等保持不变。例如： Who is she? Who are they？
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